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York YS Slide valve control

We have a 250 Ton York YS that just started driving the slide valve full open and not unloading when the water reaches setpoint. The control side appears to be working correctly but the valve is not.
I have watched it operate in the service mode where you can see the pulse for load and unload signals. With gages attached to both sides of the actuator you can see the pressure go up on the unload side but the valve does not move. If you go to manual and give it a constant unload signal it will drive the valve closed. Same pressure rise.
The Technician has already changed out the solenoid valve part that is attached to the top of the 4 Way directional valve sub plate.
Has anyone had this problem?

Slide Valve

The slide valve is operated via oil pressure. The slide valve is stuck. There should be a 1/4" access port on the end of the slide valve piston. Remove and force slide valve to move. This is the process for a Trane screw. Im not entirely sure for a york, but its very similiar. There should be a service bulletin. Hope it helps

Before you start in the wrong direction, your SV is not stuck. If it were, it wouldn't load and unload when in service mode with a constant signal. From your explanation, it sounds like the slide valve piston seals may be bypassing oil from one side of the cylinder to the other. The key is that the SV loads/unloads and the controls work, but the pulse width of the load/unload signals won't keep up with what the valve wants to do on it's own during normal operation.

York SV PROBLEM

One of our techs,diagnosed this problem yesterday. Turns out
That the intern seals are damaged. Works fine in manual mode,
But wouldn't unload in remote mode. Will have to pull
Compressor and replace. Not sure personally, if it could be field
Repair. He has 22 years in business with York, I trust his
Judgement.